Method and device for disinfectant production

ABSTRACT

The present invention relates to a technology for producing the production of disinfectants by diaphragm electrolysis of the aqueous solution of sodium chloride. Disinfectants are used in agriculture, public health care and medical institutions, public water supply systems and elsewhere. 
     The purpose of the this invention is to provide the means for producing disinfectants with the adjusting range of the pH value from 2.5 to 8.5 by using devices with various capacities ranging from 1 to 600 g active chlorine per hour, while decreasing the consumption of electric energy and sodium chloride for the production of 1 g of active chlorine over two times compared to prototype methods, and reducing the consumption of fresh water for producing of waste catholyte. The purpose of the present invention is accomplished by processing the concentrated aqueous solution of sodium chloride in anode and cathode compartment at a lower flow rate, using the flow of fresh water through the inner space of tubular cathode for cooling the solution.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Estonian Patent Application No.P201000095, filed on Dec. 30, 2010, which application is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to an electrochemical technology for theproduction of disinfectants by diaphragm electrolysis.

BACKGROUND

Estonian Patent application No. P201000069 describes a method for theproduction of disinfectants and an electrolyzer for the execution of themethod disclosed therein, in which part of a fresh water flow is usedboth for cooling a cathode compartment and for the reduction of theconcentration of active chlorine in a co-mixer of the electrolyzer. Adrawback to this method is that the flow rate passing through thecathode compartment (0.4-0.8% of the disinfectant flow) remains below2.4 l/t in devices with a low capacity (up to 300 l/t) and it requiresthe attention of personnel or the use of pressure pumps. Patents RU2297980 and U.S. Pat. No. 5,985,110 disclose methods using a cylindricaldiaphragm electrolyzer and the solution of sodium chloride as anelectrolyte. In the method disclosed in RU 2297980, the whole flow offresh water is mixed with sodium chloride and after mixing, the flow isdivided between anode and cathode compartments in a selected ratio,turning the flows into anolyte and catolyte, respectively. Anolytefunctions as a disinfectant, while catolyte has often no applications.The pH value of the disinfectant is adjusted in a range from 2.5 to 5.5by changing the ratio between the flows from the anode and cathodecompartments.

In method disclosed in U.S. Pat. No. 5,985,110, the whole flow of freshwater is mixed with sodium chloride; after mixing, the whole flow isguided to a cathode compartment. After flowing out from the cathodecompartment and the electrolyzer, some of the catolyte is guided towaste and the rest of the catolyte to the anode compartment. From theanode compartment comes out anolyte, which forms the disinfectant. ThepH value of the disinfectant is adjusted in the range from 5.5 to 8.5 ofthe discharged catolyte, meaning changing the ratio between the flowspassing through the anode and cathode compartments. A circumstance thatarises from these known methods, and which could be considered a commondrawback to methods disclosed in RU 2297980 and U.S. Pat. No. 5,985,110is that the solution of sodium chloride passing through the anodecompartment has a low level of mineralization (up to 8 g/l—a quantityequal with the quantity of the produced disinfectant), resulting in theconsumption of over 30 W of electrical energy and 12 g of sodiumchloride for the production of 1 g of active chlorine. What is needed isa method to reduce mineralization arises from the aspect that with theequal concentration of active chlorine and pH level, the bestdisinfectants by their bactericidal and corrosion preventive effect aresubstances with a lower content of sodium chloride. Reducing theconsumption of sodium chloride per 1 g of active chlorine with the knownmethods disclosed in RU 2297980 and U.S. Pat. No. 5,985,110 would meanthe reduction of anode and cathode flows, an increase in the electricalresistance between electrodes, a decrease in current intensity and ashortage of electrical energy for the production of the requiredquantity of active chlorine. Traditionally, these problems are solvedby: increasing the voltage of electrodes, reducing the distance betweenelectrodes and using a thinner membrane, multiple circulation of flowsthrough the electrode compartments together with the use of externalcooling equipment, and several consecutive electrolyzers to reduce theflow rate passing through one electrolyzer. The technical solutions forthe reduction of the consumption of sodium chloride are described inmore detail for example in patents RU 2130786, RU 2248940, RU 2350692,WO 2006098660 and U.S. Pat. No. 5,783,052; however, with all thesesolutions the electrolyzers, equipment and methods become substantiallymore complex.

The equipment necessary for the execution of the methods disclosed in RU2297980 and U.S. Pat. No. 5,985,110 are described for example in patentsRU 2079575 and U.S. Pat. No. 5,871,623. The parts of devices RU 2079575and U.S. Pat. No. 5,871,623 are as follows: a cylindrical diaphragmelectrolyzer with coaxially located anode, cathode and membrane; asource of electrical energy, a supply pipe for fresh water, a mixingunit for fresh water and sodium chloride, a supply pipe to feed sodiumchloride to electrode compartments in a quantity that equals with thesummed amount of produced disinfectant and disposed catolyte; and valvesfor adjusting the ratio of flows passing through the anode and cathodecompartments. In the device disclosed in U.S. Pat. No. 5,871,623 thereis also a discharge for catolyte after flowing out from the electrolyzerand before the anode compartment. The drawback to these prior artdevices is that each one of these is designed for realizing only onemethod—either the method disclosed in RU 2297980, which yields adisinfectant with the pH value from 2.5 to 5.5, or the method disclosedin U.S. Pat. No. 5,985,110, which yields a disinfectant with the pHvalue from 5.5 to 8.5; at this the same consumer may need simultaneouslydisinfectants with different pH values in case of a differenttechnology, obtained on the basis of the diaphragm electrolysis ofsodium chloride. For example, a farmer is recommended to use adisinfectant with the pH value 3.0-3.5 in the pre-sowing treatment ofgrain seeds, a pH value 7.0-8.5 in disinfecting the milking equipment, apH value 2.5-3.5 in the production of silage, and a pH value 6.0-7.5 indisinfecting the drinking water of animals for fattening, etc. Thereby,in practical activities, a relatively wide pH range is required. Inaddition, the design of electrolyzers used in the known methods of RU2079575 and U.S. Pat. No. 5,871,623 does not allow the reduction of theconsumption of sodium chloride without having applied externalcirculation and cooling circuits or supplementary electrolyzers. Anadditional drawback to the equipment used to employ these known methodsis that external factors have a major impact on the execution of themethod: a random increase in supply voltage entails a change in thequality of the disinfectant and failure of the device, switching on thedevice involves possible current surges and the supply may beautomatically switched off, which may not always be noticed by theoperator and the device produces to the collection tank, brine insteadof the disinfectant.

SUMMARY

A method and a device for the production of a disinfectant with a pHvalue in the range from 2.5 to 8.5. The disclosed method and device isconfigured to use a lower consumption of sodium chloride and electricalenergy per 1 g of produced active chlorine in comparison with the knownmethods and devices, and experiences reduced losses of fresh water inconnection with the discharge of catholyte for the adjustment of the pHvalue while maintaining the geometric dimensions of the electrodes andthe mutual distances, and increasing the reliability of the execution ofthe method.

According to one aspect of the disclosure, a method for the productionof the disinfectant involves treatment with an aqueous solution ofsodium chloride in a diaphragm electrolyzer with an inner tubularcathode, and foresees the following differences. The solution of sodiumchloride planned for the treatment in electrode compartments has beenprepared of only one part of fresh water, while the other part of freshwater cools a cathode compartment, passing through its hollow innerspace and entering an extension of an anode compartment in a co-mixer ofthe electrolyzer, mixing there with anolyte arriving from the anodecompartment and forming a disinfectant with the required concentrationof active chlorine. The sodium chloride solution is guided to the anodecompartment in an amount of at least 5 l/t per 1 dm² of the anodecompartment. The solution guided to the cathode compartment has thequantity of not less than 4 l/t.

For the production of a disinfectant, a device is proposed for theexecution of the method, comprising following parts: a source of freshwater, a tank of sodium chloride concentrate, a mixing unit for sodiumchloride concentrate, adjustment valves for control of the flows in theanode and cathode compartments, an adjustment valve for catholytedischarge, a source of direct current, a cylindrical electrolyzer with acoaxially located anode, cathode and membrane with an opening in a topcover for the discharge of the disinfectant and an opening for theremoval of the catholyte together with hydrogen; a converter ofelectrical energy from external sources, with the characteristic featureof a tubular inner cathode of the electrolyzer together with coversincorporating end openings for the entry and exit of fresh water. In theupper cover of the electrolyzer there is an opening for fresh water toenter into the extension of the anode compartment, fitted with aninjector located at the same height with the discharge opening for thedisinfectant. In the upper cover there is also a second opening for thedischarge of the solution from the cathode compartment, located higherthan the catolyte flow directed to the anode compartment, with thecharacteristic feature of the inlet of the anode compartment connectedto pipes supplied with valves and a mixing unit for sodium chloride andfresh water, also with the lower outlet in the upper cover of theextension of the anode compartment. A further characteristic of thedevice developed for the production of disinfectants is that theassembly contains devices for the prevention of rapid growth in consumedpower, prevention of peak loads in the power network during switching onand for protection against overcurrent during operation, and also athermal switch located on the anode compartment of the electrolyzer.

A feature of the disclosed method is in that sodium chloride solution isguided to the anode and cathode compartments, the concentration of whichhas been increased by 60% to 150% in comparison to known prior artmethods on account of preparing the solution with the part of the freshwater that is used in the process of obtaining the disinfectant. First,the second part of the fresh water is used for cooling the cathodecompartment, then again to dilute the anolyte that had obtained a highcontent of active chlorine in the anode compartment, and for theproduction of a disinfectant complying with the requirements of theconsumer, but not more than 2 g of active chlorine per one litre. Theflow rate through the anode compartment is not less than 5 l/t per 1 dm²of anode. The flow through the cathode compartment is not less than 4l/t. The pH value is adjusted in the range from 2.5 to 8.5 by changingthe routes of sodium chloride solution and the ratio of flows from theelectrode compartments.

The device disclosed herein that may be used for the production ofdisinfectants has an electrolyzer with a tubular internal cathode andthat is cooled with fresh water that is flowing inside the cathode andis then used for the production of the disinfectant in a co-mixer of thesame electrolyzer. The inlet of fresh water to the co-mixer is suppliedwith an injector. The device includes a pipe with a valve to feed thefirst part of fresh water to the hollow internal space of the cathode,and a pipe to feed the second part of fresh water to the sodium chloridemixer. In addition, the device for the production of disinfectantsincludes a hydraulic system to feed the solution of sodium chloride tothe anode inlet of the electrolyzer from different sources: one pipewith a valve connects the inlet of the anode with the mixing unit forfresh water and sodium chloride concentrate, and a second pipe with avalve connects the inlet of the anode with the lower outlet of thecathode compartment in the upper cover of the electrolyzer. When thefirst valve is open, the other is closed; when the first is closed, theother is open.

The device for the production of disinfectant may also be supplied witha thermal switch located on the external surface of the anode, and witha converter of electrical energy supplied from external sources thatincludes devices for the prevention of rapid growth in consumed power,prevention of peak loads during switching on and for protection againstovercurrent during operation.

There is a reason why the method for the production of disinfectant andthe characteristic properties of the device for the execution of themethod and the achieved technical result are connected—if a solution ofsodium chloride guided to the anode compartment is produced only fromthe fresh water planned for the production of disinfectants, thesolution arriving in the anode compartment has the content of sodiumchloride of more than 11 g/l, i.e. with a higher concentration of sodiumchloride and in a lower quantity in comparison to the prior art devicesand methods. A relatively smaller amount of the solution passes throughthe anode compartment in a significantly longer time, wherefore moreelectrical power is spent on each gramme of sodium chloride, allowing ahigher number of sodium chloride molecules to complete theelectrochemical reaction and generating a bigger quantity ofhypochlorous acid and other components of active chlorine from the samequantity of sodium chloride. At this, the anolyte evolving from theanode compartment has a high concentration of active chlorine that isreduced to the value corresponding to the needs of the consumer alreadybefore the disinfectant is discharged from the electrolyzer, whichoccurs in the co-mixer, where the anolyte is merged with the part of thefresh water that had been used for the cooling of the cathode. Using acertain amount of fresh water for the cooling of the cathode makes itpossible to have a small part of the sodium chloride solution passthrough the cathode compartment, obtain the catolyte concentrate with alow temperature at the outlet of the cathode compartment, and to protectthe electrolyzer against overheating. If the whole quantity of catolyteis guided to disposal after it has flowed out from the cathodecompartment, then the lower flow passing through the cathode compartmentreduces the water flow rate. In comparison with the prior art, the waterflow rate becomes lower also with the adjustment of the pH value at thedischarge of catolyte, since the quantity of the catolyte concentratedischarged to obtain the same change in the pH value is smaller than thequantity of the catolyte. The inventors of the present disclosure havedetermined through tests that the flow of more than 4 l/t passingthrough the cathode compartment requires practically no attention ofpersonnel and increases the reliability of the process. Based onexperiments it was also found that the flow passing through the anodecompartment is optimum both from the aspect of the temperature of sodiumchloride solution and the feasible use of sodium chloride, starting fromthe flow rate of 5 l/t per 1 dm² of the anode surface facing thecathode.

Using only a part of the fresh water to dissolve sodium chloride causesthe sodium chloride solution with a higher concentration (more than 11g/l) to enter the electrode compartments. The presence of sodiumchloride solution with a higher concentration reduces the electricalresistance between electrodes, contributing to the achievement of thesame current intensity with a lower voltage and saving electricalenergy.

The upper outlet of the cathode compartment is intended for discharginghydrogen from the electrolyzer, which reduces the pressure in the mixingunit for fresh water and sodium chloride concentrate, ensures uniformsupply of sodium chloride to the electrolyzer and a stable quality forthe disinfectant, degasses the inlet flow of the anode and reduces itselectrical resistance; the upper outlet is also used for dischargingcatolyte during the adjustment of the pH and for guiding the catolyte tothe external environment.

The adjustment of the pH value of disinfectant from the range of 2.5 to5.5 to the range of 5.5 to 8.5 and back is conducted by changing theroute of flows. To obtain a disinfectant with the pH value in the rangeof 2.5 to 5.5, the flow is guided in parallel to the anode and cathodecompartments after the mixing unit for the sodium chloride concentrate.Adjustment of pH within the named range occurs by changing the ratio offlows passing through the anode and cathode compartments. To obtain adisinfectant with a pH value in the range of 5.5 to 8.5, after themixing unit for the sodium chloride concentrate the flow is guided firstto the cathode compartment, then to degassing in the extension of thecathode compartment, and then to the inlet of the anode compartment viathe lower outlet of the cathode compartment through a pipe with an openvalve. The partial adjustment of pH in this range is conducted bydischarging some of the catolyte together with hydrogen through theupper outlet of the cathode compartment.

Using an injector to enter fresh water to the co-mixer facilitates themovement of the anolyte flow from the anode compartment to the co-mixerand supports the stability of that flow size.

Supplying the converter of electrical energy with devices to avoid thetemporary overload of the power network at the moment of switching onthe electrolyzer and to prevent possible switching off of the instrumentdue to the tripping of an automatic fuse, to limit overcurrent and toavoid rapid increase in consumed power (thermal switch on the surface ofthe anode) increases the reliability of the method in case of changes inexternal factors.

Thereby the developed method and the device executing the method providea technical solution, which results in a reduced consumption of sodiumchloride, electrical power and fresh water, and in a bigger adjustmentrange of the pH value in one device, with stability, simplicity andavailability.

Both in case of the prior art methods and the developed method, testswere carried out to compare the consumption of electrical energy, sodiumchloride and fresh water in the production of disinfectants with thesimilar pH value and concentration of active chlorine. The methods werecompared, using electrolyzers with the anode, cathode, membrane andanode shield of the same material, anode, cathode and membrane withsimilar dimensions and the same distance between electrodes. With theyield of 40 l/t, the surface area of the anode was 1.55 dm², with theyield of 120 l/t it was 3.48 dm². In the interest of more convenientdescription, the following working names were used for the methods:

-   -   the method of RU 2079575 with a separate inlet to the anode and        cathode compartments—(A+K);    -   the method corresponding to the disclosure, with a pH in the        range of 2.5 to 5.5—(A+2K);    -   the method of U.S. Pat. No. 5,871,623 with the electrolyte        flowing consecutively through the cathode and anode        compartment—(ANK);    -   the method corresponding to the disclosure, with a pH in the        range of 5.5 to 8.5—(AN2K).

Test results indicate that the method presented in the disclosure ismore economical than the existing methods (A+K) and (ANK). Powerconsumption is reduced by 30-50%, overall consumption of sodium chlorideper 1 g of active chlorine is reduced by 40-50%. The discharge of freshwater to the drain in the form of catolyte, necessary for the adjustmentof the pH value of the anolyte to the approximately same value, isreduced by 1.5 times, a similar quantity of the discharge in case of thepresented method gives again a good result for the efficient pHadjustment. Test results are presented in tables 1 and 2.

The disclosed method makes it possible to manufacture devices for theproduction of disinfectants with a broad range of pH values and a lowerconsumption of sodium chloride, fresh water and power in comparison withsimilar methods; the devices are convenient and simple and suitable forthe use by a wide circle of consumers, including agricultural farms,health care and medical institutions and other social care institutions.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a plan of a device that corresponds to and exemplaryconfiguration of the disclosure, with arrows marking the flows of fluidsparticipating in the developed method.

DETAILED DESCRIPTION

The possible execution of an exemplary arrangement of a methodcorresponding to the disclosure is described in the following examples.The method prescribes that before mixing with the anolyte and the sodiumchloride concentrate, fresh water flows along the same path whenproducing a disinfectant both in the pH range of 2.5 to 5.5 (A+2K) and5.5 to 8.5 (AN2K).

The flow of fresh water 1 entering from external source is divided intotwo parts: flow 2, which is intended for mixing with the anolyte andcooling of cathode 3, and flow 4, which is intended for mixing withsodium chloride.

Flow 2 is adjusted on the basis of volume with valve 5, and is guidedthrough opening 6 in the cover 7 of cathode 3 to the hollow inner space8 in the cathode. Fresh water passes through the hollow interior of thecathode 3 and cools it, then flows through opening 9 in the cover 10 ofcathode 3 through pipe 11 to the extension 12 of the anode compartment26, entering the co-mixer 14 through inlet 15 supplied with injector 16.

At the same time, flow 4 passes to a mixing unit 17 of sodium chloridesolution, to which the solution of sodium chloride arrives from a tank18 in a quantity that is adjusted with valve 19.

If the consumer requires a disinfectant with a pH value in the range of2.5 to 5.5 (A+2K), then valve 20 is opened to pipe 21 that connectsinlet 22 with outlet 24 from extension 25 of anode compartment 26, andthe solution of sodium chloride is guided after exiting mixing unit 17in parallel to anode compartment 13 through pipe 21 and to cathodecompartment 3 through pipe 27. Valve 28 on pipe 27 is intended for theadjustment of the catolyte flow in the cathode compartment 3 in aquantity of not less than 4 litres per hour for the purpose of adjustingthe pH value of the disinfectant in the range of 2.5 to 5.5. The biggerthe flow in the cathode compartment 3 with the same flow in the anodecompartment 13, the lower the pH of the disinfectant. Catholyte arrivesinto extension 25 of anode compartment 26 and is discharged togetherwith hydrogen in case of a completely open valve 30 through an upperoutlet 29 to the external environment. The solution of sodium chlorideentering into anode compartment 13 through pipe 21 is turned intoanolyte by electrical energy, containing active chlorine in the form ofhypochlorous acid, hypochlorite ions, chlorine dioxide, etc. with theapproximate concentration of 2 g/l. The anolyte arrives into extension12 of anode compartment 13 located in co-mixer 14. There the anolyte ismerged with fresh water that enters through opening 15, and theconcentration of the active chlorine is adjusted according to the normof the disinfectant. The disinfectant is guided through outlet 31 to theconsumer. Injector 16 reduces the hydraulic pressure of the fresh waterarriving to the co-mixer 14 to the movement of anolyte in the anodecompartment and to other flows that are consecutively hydraulicallyconnected to the anode compartment, including the continuous feeding ofthe sodium chloride concentrate to mixing unit 17, which is especiallyimportant in order to ensure the stability of the process.

If the consumer requires a disinfectant in the pH range of 5.5 to 8.5(AN2K), then valve 20 is closed while valve 23 is open. The flow offresh water follows the same route as in case of method (A+2K). Thesolution of sodium chloride arrives into cathode compartment 26 throughpipe 27. The flow rate in pipe 27 is adjusted with valve 28 in a volumethat equals with the flow in the anode compartment, i.e. not less than 5l/t per 1 dm2 of anode, which is increased by discharging catolyte inorder to adjust the pH value of the disinfectant.

In the cathode compartment, the solution of sodium chloride turns withthe impact of electricity into catolyte with a higher content of sodiumchloride.

From cathode compartment 26 the catolyte is guided to extension 25 ofthe cathode compartment, in which hydrogen and some of the catolyte aredischarged through upper outlet 29, which is necessary in order toadjust the ratio between the flows in the electrode compartments andtogether with that also for the adjustment of the pH value of thedisinfectant within the range of 5.5 to 8.5. The quantity of dischargedcatolyte is adjusted with valve 30. The more catolyte is discharged, thelower the pH value. Some of the catolyte arrives into anode compartment13 through lower outlet 24 along pipe 32 (with completely open valve 23)via inlet 22. In the anode compartment the catolyte with high content ofsodium chloride is turned into anolyte via electrical energy, with theapproximate concentration of the active chlorine 2 g/l. The anolyte thatcontains hypochlorous acid, hypochlorite ions, chlorine dioxide, etc. isguided to extension 12 of anode compartment 13 located in co-mixer 14.Similarly to method (A+2K), in the co-mixer the anolyte is merged withfresh water that enters through opening 15, and the concentration ofactive chlorine is adjusted to the norm of the disinfectant. Thedisinfectant is discharged to the consumer through outlet 31.

For the execution of the electrochemical processes of the method and forthe auxiliary power consumption of the device, the device includes aconverter 33 for external power supply, which incorporates a device forlimiting rapid increases in consumed power, a protection device for theprevention of peak loads in the power network during switching on and aprotection against overcurrent during operation. Such design ofconverter 33 increases the reliability of the device, protecting itagainst possible overloads in the supply network in case of the method.

Since generally the consequences of a majority of deviations from theoperating modes provided in this method are increases in the temperatureof the anolyte and anode, then the device is also equipped with thermalswitch 34 installed to anode 35, breaking the supply current to theelectrolyzer until the temperature has returned to the safe level.

TABLE 1 Test numbers 1 2 3 4 Indicators Unit A + κ A + 2κ ± % A + κ A +2κ ± % A + κ A + 2κ ± % A + κ A + 2κ ± % Disinfectant l/t 40 40 40 40120 120 120 120 quantity Flow rate in l/t 20 5 12 4 40 12 20 4 cathodecompartment Flow rate in anode l/t 40 10 40 10 120 20 120 20 compartmentFlow rate inside l/t — 30 — 30 — 100 — 100 cathode Total flow rate l/t60 45 52 44 160 132 140 124 Content of active mg/l 505 500 510 510 500500 500 500 chlorine Concentration of g\l 4.4 7.3 +66 4.7 8.0 +70 6.312.5 +99 7.1 12 +69 sodium chloride at anode compartment inletConsumption of W 41.6 18.0 −57 41.2 17.6 −57 31.0 14.3 −54 31.0 14.3 −54electrical energy Anolyte pH 2.6 2.7 3.5 3.3 2.9 2.9 3.65 4.5 Drainedcatolyte l/t 20 5 −75 12 4 −66 40 12 −70 20 4 −75 Sodium chloride g/g13.0 5.5 −58 12.0 5.5 −54 16.9 4.2 −75 16.5 4.0 −76 consumption

TABLE 2 Test numbers 5 6 7 8 Indicators Unit ANK AN2K ± % ANK AN2K ± %ANK AN2K ± % ANK AN2K ± % Disinfectant l/t 40 40 40 40 120 120 120 120quantity Flow rate in l/t 40 10 45 15 120 20 120 36 cathode compartmentFlow rate in anode l/t 40 10 40 10 120 20 160 20 compartment Flow rateinside l/t — 30 — 30 — 100 — 100 cathode Total flow rate l/t 40 40 45 45120 120 160 136 Content of active mg/l 500 500 500 500 500 500 500 500chlorine Concentration of g\l 6.7 12.4 +85 6.8 11.1 +63 8.6 21.0 +1446.8 17.2 +152 sodium chloride at anode compartment inlet Consumption ofW 37.5 17.6 −53 37.5 18.0 −52 32.5 14.7 −55 34.0 15.3 −55 electricalenergy Anolyte pH 8.8 9.0 8.2 7.7 8.4 8.8 6.9 6.1 Drained catolyte l/t —— 5 5 — — 40 16 −80 Sodium chloride g/g 13.3 6.2 −53 15.2 8.3 −45 17.27.0 −59 18.1 10.3 −43 consumption

1.-6. (canceled)
 7. A method for production of disinfectant, comprisingfollowing stages: converting an aqueous solution of sodium chloride intoanolyte in an anode compartment of a diaphragm electrolyzer and intocatolyte in a cathode compartment, a flow of the solution moving in theanode and cathode compartments in one direction from bottom to top,obtaining disinfectants with a pH value in a range of 2.5 to 5.5 fromthe solution of sodium chloride arriving to the anode compartmentimmediately after a mixer of a sodium chloride concentrate and freshwater, disinfectants with a pH value in a range of 5.5 to 8.5 from thesolution of sodium chloride arriving to the anode compartment aftertreatment in the cathode compartment; changing the pH of disinfectant inthe ranges of 2.5 to 5.5 and 5.5 to 8.5 by changing a ratio of flowrates in the anode and cathode compartments with the adjustment of adischarge of catholyte to an external environment; discharging thedisinfectant from the electrolyzer with a selected concentration ofactive chlorine; wherein only the solution of sodium chloride is treatedin the anode and cathode compartments, which has been prepared with afirst part of the fresh water used in the production of thedisinfectant, a second part of the fresh water being guided first insidethe cathode compartment and then to a co-mixer of the electrolyzer,where the second part of the fresh water is mixed with the anolytearriving from the anode compartment, resulting in a disinfectant with aconcentration of active chlorine of up to 2 g/l and with a pH with apreset value in the range of 2.5 to 8.5.
 8. The method according toclaim 1, wherein the flow rate of sodium chloride solution passingthrough the anode compartment is not less than 5 l/t per 1 dm² of ananode surface facing the cathode.
 9. The method according to claim 1,wherein the flow rate of sodium chloride solution passing through thecathode compartment is not less than 4 l/t.
 10. The method according toclaim 1, wherein the concentration of sodium chloride in the solutionpassing through the anode compartment is up to 20 g/l.
 11. The methodaccording to claim 1, wherein hydrogen is removed from the cathodecompartment before the catolyte is guided to the anode compartment.